<template>
    <div
            class="demo-block"
            :class="[blockClass, { 'hover': hovering }]"
            @mouseenter="hovering = true"
            @mouseleave="hovering = false">
        <slot name="source"></slot>
        <div class="meta" ref="meta">
            <div class="description" v-if="$slots.default">
                <slot></slot>
            </div>
            <slot name="highlight"></slot>
        </div>
        <div
            class="demo-block-control"
            ref="control"
            @click="isExpanded = !isExpanded">
        <transition name="arrow-slide">
            <i :class="[iconClass, { 'hovering': hovering }]"></i>
        </transition>
        <transition name="text-slide">
            <span v-show="hovering">{{ controlText }}</span>
        </transition>
        </div>
    </div>
</template>

<style lang="less">
    .demo-block {
        border: solid 1px #ebebeb;
        border-radius: 3px;
        transition: .2s;

        &.hover {
            box-shadow: 0 0 8px 0 rgba(232, 237, 250, .6), 0 2px 4px 0 rgba(232, 237, 250, .5);
        }

        code {
            font-family: Menlo, Monaco, Consolas, Courier, monospace;
        }

        .demo-button {
            float: right;
        }

        .source {
            padding: 24px;
        }

        .meta {
            background-color: #fafafa;
            border-top: solid 1px #eaeefb;
            overflow: hidden;
            height: 0;
            transition: height .2s;
        }

        .description {
            padding: 20px;
            box-sizing: border-box;
            border: solid 1px #ebebeb;
            border-radius: 3px;
            font-size: 14px;
            line-height: 22px;
            color: #666;
            word-break: break-word;
            margin: 10px;
            background-color: #fff;

            p {
                margin: 0;
                line-height: 26px;
            }

            code {
                color: #5e6d82;
                background-color: #e6effb;
                margin: 0 4px;
                display: inline-block;
                padding: 1px 5px;
                font-size: 12px;
                border-radius: 3px;
                height: 18px;
                line-height: 18px;
            }
        }

        .highlight {
            pre {
                margin: 0;
            }

            code.hljs {
                margin: 0;
                border: none;
                max-height: none;
                border-radius: 0;

                &::before {
                    content: none;
                }
            }
        }

        .demo-block-control {
            border-top: solid 1px #eaeefb;
            height: 44px;
            box-sizing: border-box;
            border-bottom-left-radius: 4px;
            border-bottom-right-radius: 4px;
            text-align: center;
            margin-top: -1px;
            color: #d3dce6;
            cursor: pointer;
            position: relative;
            font-size: 0;
            &.is-fixed {
                position: fixed;
                bottom: 0;
                width: 868px;
            }

            i {
                display: inline-block;
                font-size: 16px;
                line-height: 44px;
                transition: .3s;
                &.hovering {
                    transform: translateX(-40px);
                }
            }

            > span {
                position: absolute;
                transform: translateX(-30px);
                font-size: 14px;
                line-height: 44px;
                transition: .3s;
                display: inline-block;
            }

            &:hover {
                color: #409EFF;
                background-color: #f9fafc;
            }

            & .text-slide-enter,
            & .text-slide-leave-active {
                opacity: 0;
                transform: translateX(10px);
            }

            .control-button {
                line-height: 26px;
                position: absolute;
                top: 0;
                right: 0;
                font-size: 14px;
                padding-left: 5px;
                padding-right: 25px;
            }
        }
    }
</style>

<script type="text/babel">
    export default {
        data() {
            return {
                hovering: false,
                isExpanded: false,
                fixedControl: false,
                scrollParent: null,
                langConfig: {
                    "hide-text": "隐藏代码",
                    "show-text": "显示代码",
                    "button-text": "在线运行",
                    "tooltip-text": "前往 jsfiddle.net 运行此示例"
                }
            };
        },

        props: {
            jsfiddle: Object,
            default() {
                return {};
            }
        },

        methods: {
            scrollHandler() {
                const {top, bottom, left} = this.$refs.meta.getBoundingClientRect();
                this.fixedControl = bottom > document.documentElement.clientHeight &&
                    top + 44 <= document.documentElement.clientHeight;
            },

            removeScrollHandler() {
                this.scrollParent && this.scrollParent.removeEventListener('scroll', this.scrollHandler);
            }
        },

        computed: {
            lang() {
                return this.$route.path.split('/')[1];
            },

            blockClass() {
                return `demo-${ this.lang } demo-${ this.$router.currentRoute.path.split('/').pop() }`;
            },

            iconClass() {
                return this.isExpanded ? 'el-icon-caret-top' : 'el-icon-caret-bottom';
            },

            controlText() {
                return this.isExpanded ? this.langConfig['hide-text'] : this.langConfig['show-text'];
            },

            codeArea() {
                return this.$el.getElementsByClassName('meta')[0];
            },

            codeAreaHeight() {
                if (this.$el.getElementsByClassName('description').length > 0) {
                    return this.$el.getElementsByClassName('description')[0].clientHeight +
                        this.$el.getElementsByClassName('highlight')[0].clientHeight + 20;
                }
                return this.$el.getElementsByClassName('highlight')[0].clientHeight;
            }
        },

        watch: {
            isExpanded(val) {
                this.codeArea.style.height = val ? `${ this.codeAreaHeight + 1 }px` : '0';
                if (!val) {
                    this.fixedControl = false;
                    this.$refs.control.style.left = '0';
                    this.removeScrollHandler();
                    return;
                }
                setTimeout(() => {
                    this.scrollParent = document.querySelector('.page-component__scroll > .el-scrollbar__wrap');
                    this.scrollParent && this.scrollParent.addEventListener('scroll', this.scrollHandler);
                    this.scrollHandler();
                }, 200);
            }
        },

        mounted() {
            this.$nextTick(() => {
                let highlight = this.$el.getElementsByClassName('highlight')[0];
                if (this.$el.getElementsByClassName('description').length === 0) {
                    highlight.style.width = '100%';
                    highlight.borderRight = 'none';
                }
            });
        },

        beforeDestroy() {
            this.removeScrollHandler();
        }
    };
</script>
